REVISION OF THE KING SNAKES. 67 



This form seems not to differ in size or proportions from hoylii. 

 The tail varies from 0.090 to 0.140 of the total length (males, .121 to 

 .132, average, .127; females, .093 to .128, average .117). The 

 largest specimen examined was from the Graham Mountains, Arizona, 

 and measured, 1,204 mm. 



The pattern is composed of white annuli separated by black, and 

 varying in number from 29 to 45 (average 37). It differs from 

 hoylii in that the most of the white scales are marked basally with 

 dark brown, which not infrequently extends irregularly over the 

 scales so as to greatly obscure the rings. The latter are narrow on 

 the back, 1 to 2^ scales in width, widening on the side to about 2 

 to 5 scales, and traversing the belly. They may be divided on the 

 midventral line and alternated instead of joined, and this may 

 occur less frequently above. 



Characteristic of the group are the white bars across the prefrontals 

 and internasals, and the white centers on rostral, nasals, loreal, 

 oculars, and labials. Beneath the eye there is usually a rather con- 

 spicuous enlargement of the common dark border of the third and 

 fourth upper labials. Other markings on the head are infrequent. 

 There may be small white dots on supraoculars, anterior temporals, 

 anterior portion of frontal, and rarely on the edges of the parietals. 

 On the first scales behind the parietals there may be a small cluster 

 of white spots, the homologue of the first white band or ring, which, 

 in all members of the group, may at times be fairly well developed. 



The belly is usually crossed by the continuations of the black and 

 white rings, and, like the dorsal white scales, the white ventral 

 plates are usually conspicuously edged basally with dark brown. 



The skull is like that of hoylii. The dentition, as indicated by a 

 few specimens, is as follows: MaxiUary teeth, 13 to 16, the last two 

 somewhat stouter than those preceding; mandibular teeth, 14 to 17, 

 the anterior the larger; palatines, 9 or 10; pterygoids, 12 to 19. 



The penial characters are very much like those of splendida. The 

 organ is bilobed, and has a small smooth area at the distal end. The 

 calyces are few, and their fringes may be fairly conspicuous or very 

 short. Minute spines are barely distinguishable over nearly as much 

 area as covered by the large spines. 



To distinguish this form from conjunda and from hoylii, see the 

 table under the description of the latter. From splendida it may be 

 known by the fact that the white annuli are not joined on the sides, 

 but are completely separated by the black interspaces. 



Hahitat and liahits. — Except for C. L. Camp's note for the vicinity 

 of Yuma, that this form "lives among cottonwoods and thick growth 

 along the river bottom," there are, apparently, no observations 

 available on the natural history of yumensis. Such observations 

 would be very desirable for comparison with those of splendida and 



